Multifunctional antenna

ABSTRACT

An improved antenna array comprises at least four antennas. One antenna receives satellite signals, especially digital satellite signals. One antenna receives terrestrial signals, particularly terrestrially transmitted radio programs. One antenna is provided for the mobile radio sector. One antenna determines the geoposition. The at least four antennas are disposed in a given order such that antenna, antenna, antenna, and antenna are located one behind another from one end of the chassis.

This application is the U.S. national phase of international applicationPCT/EP2004/006863 filed 24 Jun. 2004 which designated the U.S. andclaims priority of DE 103 30 087.2, filed 3 Jul. 2003, the entirecontents of each of which are hereby incorporated by reference.

The invention relates to a multifunctional antenna as claimed in thepreamble of claim 1.

A satellite-based radio system which operates with only a small numberof satellites distributed in orbit is used, in particular, in the USA.The aim is to offer antennas for this satellite-based radio system whichhave to maintain the same minimum gain even at low elevation angles from20° and more, in particular from 25° up to an elevation of 90°.

The corresponding systems are also known in the specialist field by theexpression SDARS services, which transmit in the 2.3 GHz band. Thesatellite signals are in this case transmitted with circularpolarization.

In order to take account of these extreme conditions and to implement ahigh antenna gain even at low elevations from 20° or 25° and more,continuous attempts have been made to take account of these extremerequirements by specially designed antenna structures.

WO 01/80366 A1 has disclosed a special antenna system which containscruciform dipole that is formed from a flat material and thus forms fourquadrants which are separated from one another by the dipole walls. Aseparate, vertically extending monopole is then arranged in eachquadrant, via which the terrestrially transmitted vertically polarizedsignals can be received. The aim is that program reception be possibleby means of this second antenna arrangement whenever it is no longerpossible to receive the programs emitted in parallel on satellite,because, for example, the satellite positioned in part very low on thehorizon is shielded by mountains, buildings, tunnels etc.

In addition, for example, DE 202 07 401 U1 has disclosed a correspondingland vehicle receiving device for digital radio-frequency signals thatare provided in a prescribed frequency band, firstly at low intensity bya satellite, and secondly at a substantially greater intensity by aterrestrial transmitter in shadow zones. Since the terrestrial signalsare received with substantially greater intensity, this priorpublication proposed a Wilkinson divider, which is also denoted as a 3dB divider. Provided for this purpose in one downstream branch is afurther, that is to say a second, amplifier, which once more amplifiesthe satellite signals of low intensity by a further stage in order tohave received signals of approximately the same strength present at theoutput of the whole circuit. However, this prior publication coversneither a mobile radio antenna nor, for example, a GPS receiving antennafor geopositioning of the land vehicle.

DE 202 10 312 U1 has likewise disclosed an antenna arrangement for motorvehicles which is intended to be suitable, in particular, for receivingdigital broadcast radio signals in accordance with the North AmericanSDARS standard.

In addition, this antenna likewise comprises a rod-shaped mobile radioantenna as second antenna device. Moreover, with this antenna systemthere is no location system comparable to the GPS system forestablishing the respective position of the land vehicle.

A vehicle antenna arrangement for receiving a number of differentfrequency bands separated by gaps has also been disclosed in DE 101 33295 A1. This is an antenna arrangement with four antennas, specificallytwo broadband antennas for different mobile radio frequencies, asatellite-linked vehicle navigation antenna corresponding to the GPSsystem, and an antenna for the Satellite Digital Audio Reception SystemSDARS. It is further to be gathered in this case from the priorpublication that the SDARS antenna is intended to have a configurationboth for satellite-linked and for terrestrial operation with a verticalpolarization.

By contrast, it is an object of the present invention to provide anantenna arrangement that, firstly, is suitable for receiving satellitesignals, preferably even from satellites situated comparatively lowabove the horizon and, secondly, also is capable of receivingterrestrial signals, in particular terrestrially emitted radio programs,and which additionally also comprises at least one antenna for a mobiletelephone as well as a receiving antenna for determining thecoordinates, and thus the position, of a vehicle. The antenna isintended in this case to have the smallest possible installation space.

The object is achieved according to the invention in accordance with thefeatures specified in claim 1. Advantageous refinements of the inventionare specified in the subclaims.

It must be described as more than surprising that success has beenachieved in implementing such an antenna according to the invention forreceiving the most varied services in so compact a design. It ispossible thereby for the antenna arrangement to be accommodatedcomparatively inconspicuously in compact form in a preferably fin-likehousing on a land vehicle, that is to say a passenger car, for example,in particular in the roof area or at the transition from the roof areato the rear window.

The solution is all the more surprising since there was no indication inthe prior art that this compact solution has become possible simply andsolely through the inventive arrangement of the individual antennas forthe various services.

Specifically, experiments have shown that it is necessary per se alwaysto maintain certain minimum distances between the individual antennasfor the various services in order to be able to implement a respectivelyadequate reception quality. Experiments have shown that, for examplestarting from an antenna device in accordance with WO 01/80366 A1, itwould be necessary for an antenna device with the abovedescribed fourservices to be of extremely long construction. If, in the case of anantenna device in accordance with the abovementioned WO 01/80366 A1 aGPS antenna for determining position as well as a mobile radio antenna,for example, were to be arranged next to one another on a fin-likemounting plate in order to receive signals emitted via satellite as wellas to receive terrestrial signals, this would lead to an arrangementwith an overall length of much greater than 18 to 20 cm, as a rule.

By contrast, were it attempted to assemble comparable components moretightly in the longitudinal direction of a chassis, the result of thiswould be that the reception quality would not fulfill the requiredstipulations for the various services.

Against this background, the surprising result is to be seen in thatdespite an extremely compact arrangement overall with a high integrationdensity, it has become possible simply and solely through the differentsequence and arrangement of the individual antennas for the variousservices to construct an antenna arrangement for the various servicesthat at the same time exhibits surprisingly good reception qualities.

The most varied experiments have shown that, for example, good receptionqualities can be achieved for the various services with an antennaarrangement in which there should be provided on a chassis in a fashionrunning from the front tip to the rear end firstly a satellite receivingantenna, for example for SDARS services, subsequently a GPS antenna,then an antenna for terrestrial reception of signals, for example in theform of the terrestrially emitted SDARS services, and then a mobileradio antenna. However, this would then lead to an antenna structurewith an overall chassis length of approximately 22 cm, and this would bejudged far too large for fitting to the roof of conventional passengercars.

By contrast, however, the invention proceeds from the idea that firstlya terrestrial receiving antenna (in particular for terrestrial receptionof the SDARS services), subsequently an antenna for receiving thesignals for determining the position of the motor vehicle (for example aGPS antenna), then a satellite antenna (for example for receiving SDARSservices emitted via satellite) and, finally, a mobile radio antenna arepreferably arranged on a chassis in the shape of a boat or fin in afashion building up from front to rear (corresponding to the alignmenton the motor vehicle), or in reverse sequence. It was possible owing tothis sequence to attain an optimization which is such that theindividual services could be received with the desired receptionqualities, and that at the same time the antenna, that is to say thechassis, has a measure of length which can amount to under 18 cm,including under 17 cm without a problem. It has even emerged that theoverall length of the chassis holding the antenna can be shortened tounder 150 mm without a problem.

The antenna is explained more closely below with the aid of drawings inwhich, in detail:

FIG. 1 shows a schematic side view of the antenna according to theinvention;

FIG. 2 shows a schematic plan view of the antenna reproduced in FIG. 1;and

FIG. 3 shows a perspective illustration of the antenna arrangement witha housing cover protecting the individual antennas.

An exemplary embodiment of an antenna arrangement according to theinvention is shown in schematic side view in FIG. 1, and in schematicplan view in FIG. 2.

The antenna arrangement comprises a chassis 1, which is shaped in planview in a way comparable to a ship's hull, surfboard etc., specificallywith a comparatively narrower, leading region 3, and a middle region 5,broader by comparison therewith, and a rear region 7. The chassisusually consists of a metallic basic body, for example a metal casting.

Such a chassis is usually mounted on a motor vehicle roof, for exampleat the rear end region before the transition to the rear window, eithera cutout or a depression being provided in the body sheet at this pointin the motor vehicle, in order to position the chassis 1 thus formed ata suitable height relative to the body sheet. Here, the leading,narrower region 3 points forwards with the motor vehicle in the drivingdirection, and so the rear region 7 comes to lie rearward on thevehicle. The corresponding antenna is usually mounted in the middle ofthe vehicle and is protected in this case via a housing cover 9 thatpreferably has a body in the shape of a fin, as is to be seen in theschematic rear view in accordance with FIG. 3.

In the exemplary embodiment shown, various antennas are accommodated inthe chassis 1 below the housing cover 9, specifically, in a fashionfollowing one another from the front region to the rear region 7:

-   -   firstly, an antenna A for receiving terrestrial signals;    -   subsequently, an antenna B for determining the position of the        vehicle fitted with the antenna arrangement, for example an        antenna B for the GPS location system;    -   subsequently, an antenna C for receiving satellite signals, in        particular for receiving digital satellite signals, for example        corresponding to the SDARS services in North America; and    -   an antenna D for the mobile radio field.

The satellite antenna can be used, for example, to receive radioprograms emitted by satellite. The antenna C can be designed in thiscase for receiving digital radio-frequency signals corresponding to theSDARS services in North America. These signals are emitted in this wayin a frequency band of approximately 2.3 GHz.

However, the terrestrial receiving antenna A seated at the front can nowreceive terrestrially emitted signals, in particular terrestriallyemitted radio programs. Particularly in the USA, such antennas arerequired for receiving the SDARS services, above all because thesatellites emitting SDARS services are partly located not in theiroptimum position as vertically as possible over the receiving vehicle,but are positioned in part very low on the horizon down to an elevationangle of approximately 20° or, for example, approximately 25°. Theconsequence of this is that the signals emitted by satellites arefrequently shielded, for example in gorges, tunnels, under bridges etc.In order to permit radio programs to be received even at such locations,terrestrially placed transmission positions are provided in part so thatthe radio programs can be received in parallel in these situations viathe terrestrial antenna A.

The location system is preferably the GPS location system in worldwideuse. However, other location systems such as, for example, the Galileoone currently being planned in Europe are also suitable for receptionwith such a receiving antenna.

A mobile radio antenna D is preferably proposed at the rear end. Byvirtue of the way it is fashioned, its size etc., this mobile radioantenna can be suitable for communicating in different mobile radiobands, for example for receiving in the 900 MHz band, in the 1.8 GHzband or, for example, in the 1700 to 2170 MHz band. Consequently, themobile radio antenna can be suitable not only for receiving one of thesefrequency bands, but also for receiving two or three or in general aplurality of the frequency bands named, or other such bands. For thispurpose, the mobile radio antenna can preferably comprise a substraterising vertically in relation to the chassis 1, for example a printedcircuit board on which appropriately conducting surfaces are formed asantenna elements.

The overall length of the chassis can amount to less than 170 nm, forexample less than 160 mm or even 150 mm.

1. A multifunction antenna comprising: a chassis having a leading regionand a trailing region, at least four antennas, at least one of saidantennas being suitable for receiving digital satellite signals, atleast one of said antennas provided for receiving terrestrially emittedradial programs, at least one of said antennas provided for a mobileradio field, and at least one of said antennas provided for determininggeoposition, the antenna for receiving terrestrial signals beingprovided as a separate antenna in addition to the antenna for receivingsatellite signals, the at least four antennas being arranged in aprescribed sequence on said chassis, the antenna for receiving theterrestrially emitted signals being arranged at one end of said chassis,followed by the antenna for determining the geoposition, followed by theantenna for receiving satellite signals, and followed by the antenna forthe mobile radio field, the center-to-center distance between theterrestrial antenna and the adjacent antenna for geopositioning beingsmaller than the center-to-center distance between the geopositioningantenna and the adjacent antenna for receiving satellite signals, thecenter-to-center distance between the antenna for geopositioning and theadjacent satellite antenna being smaller than the center-to-centerdistance between the satellite antenna and the antenna for the mobileradio field, and the antenna for receiving the terrestrially emittedsignals being arranged in the leading region of the chassis such thatthe mobile radio field antenna, seated furthest therefrom, is arrangedin the trailing region on the chassis.
 2. The multifunction antenna asclaimed in claim 1, wherein at least three of said four adjacentantennas, are arranged adjacently on a longitudinal region of thechassis, which amounts to less than 60% of the overall length of thechassis.
 3. The multifunction antenna as claimed in claim 1, wherein theantenna for receiving the satellite signals comprises a patch antenna.4. The multifunction antenna as claimed in claim 1, wherein the antennafor carrying out geopositioning comprises a patch antenna.
 5. Themultifunction antenna as claimed in claim 1, wherein the antenna forreceiving terrestrial signals comprises at least a monopole.
 6. Themultifunction antenna as claimed in claim 1, wherein the antenna for themobile radio field is suitable for receiving at least in one mobileradio frequency band in at least two frequency bands.
 7. Themultifunction antenna as claimed in claim 6, wherein the antenna for themobile radio field comprises electrically conducting surfaces that areformed on a substrate.
 8. The multifunction antenna as claimed in claim1, wherein the housing has a fin-like housing cover, and the fourantennas are arranged on the chassis beneath said fin-like housingcover.
 9. The multifunction antenna as claimed in claim 1, wherein inplan view the chassis is structured like a boat.